Gas springs charged with nitrogen or other inert gas are well-known and in widespread use in connection with metal-forming die sets. Examples of such nitrogen gas springs are disclosed in U.S. Pat. No. 6,022,004 entitled “Self-Lubricating Fluid Cylinder,” U.S. Pat. No. 6,749,185 entitled “Cushion Assembly and Method,” and U.S. Pat. No. 6,796,159 entitled “Low Contact Force Spring,” all of which patents are hereby incorporated by reference. These gas springs and others are available commercially from Hyson Products, Brecksville, Ohio, U.S.A.
A need has been identified for a new type of gas spring to be used as a die separator cylinder. More particularly, a need has been found for a die separator cylinder, a group of which is adapted to be assembled into a forming die set which is used in a press, wherein the die separator cylinders provide maximum separation force to maintain the upper and lower die components in a spaced-apart relationship when the die set is put into storage, and wherein the die separator cylinder provide minimal separation force when the die set is put into use so as to have minimal effect on metal forming operations.